A screw device in which rolling elements are placed between a screw shaft and a nut is used as a mechanical element that converts the rotational motion of the screw shaft into the linear motion of the nut, or converts the linear motion of the screw shaft into the rotational motion of the nut. The screw device uses the rolling motion of the rolling element and accordingly has a feature that the light movement of the screw shaft and the nut can be obtained.
A what is called end piece screw device in which a circulation member is attached to each of axial end surfaces of the nut to circulate the rolling elements is known as a kind of screw device (refer to Patent Literature 1). In the screw device, a communicating hole penetrating the nut in the axial direction is opened in the nut. A recess communicating with the communicating hole and a helical loaded rolling element rolling groove is processed in the axial end surface of the nut. The circulation member includes a turn-around path. When the circulation member is fitted into the recess, the turn-around path of the circulation member links to the loaded rolling element rolling groove and the communicating hole of the nut to form a circulation path of the rolling elements. The circulation member is fitted into the recess of the nut, and then is firmly fixed therein with a bolt or C-shaped ring. The rolling element that has rolled to one end of the loaded rolling element rolling groove of the nut returns to the other end of the loaded rolling element rolling groove via the turn-around path of the circulation member, the communicating hole, and a turn-around path of a circulation member on the opposite side.